1. Field of the Invention
This invention relates to electrical circuit interrupting devices incorporating an arc extinguishing liquid.
2. Prior Art
It is well known in circuit breakers, switches, ring main units, switch disconnectors and other switch gear for switching electrical circuits to have relatively movable switching contacts immersed in an arc extinguishing fluid. Although mineral hydrocarbon oils are widely used for this purpose, they possess a number of disadvantages and in particular they are flammable and form flammable or explosive gases when subjected to an electric arc. It has been proposed to use various non-flammable fluids, particularly halogenated hydrocarbons, as substitutes for such mineral oil. Problems arise however with such materials, in particular the production of toxic materials when an arc occurs in the fluid.